Determination of Adhesive and Cohesive Strength in Metal Coatings Deposited by Hypersonic Metallization

. It is known that at present, methods of thermal spraying are widely used to restore and strengthen various worn-out machine parts. As a rule, metal coatings applied by thermal spraying have lower strength characteristics than solid materials. It is believed that the strength of coatings is proportional to their adhesive and cohesive strength. The value of adhesive and cohesive strength depends on various factors, including the nature of the materials and the technology of coating. An important factor characterizing the possibility of using metal coatings in various industries is the strength of adhesion of coatings to the base metal. The paper presents the determination of the adhesive and cohesive strength of coatings from different materials, applied by the method of hypersonic metallization. The results of testing the strength of metal coatings made of ER316LSi-grade wire, nichrome (Cr20Ni80) and molybdenum wire are given in the paper. Based on the results of metallographic studies, the proportion of the participation of cohesive and adhesive components in the strength of coatings has been determined, and some features of coating destruction have been described. It has been found that the participation of the cohesive and adhesive components of the coating strength differs depending on the material used. The cohesive component prevails in the strength of coatings made of high-alloy wire of the ER316LSi-grade, at which destruction mainly occurs along the coating-base boundary. For nichrome coatings and especially for coatings made of molybdenum, the cohesive component is predominant, in which the destruction of the coating occurs not along the coating-base boundary, but between the coating layers.

A Novel Cell Vertex Model Formulation that Distinguishes the Strength of Contraction Forces and Adhesion at Cell Boundaries

The vertex model is a useful mathematical model to describe the dynamics of epithelial cell sheets. However, existing vertex models do not distinguish contraction forces on the cell boundary from adhesion between cells, employing a single parameter to express both. In this paper, we introduce the rest length of the cell boundary and its dynamics into the existing vertex model, giving a novel formulation of the model that treats separately the contraction force and the strength of adhesion between cells. We apply this vertex model to the phenomenon of compartment boundary in the fruit fly pupa, recapturing the observation that increasing the strength of adhesion between cells straightens the compartment boundary, even though contraction forces at cell boundaries remain unchanged. We also discuss possibilities of the novel vertex models by considering the stretching of a cell sheet by external forces.

COMPARATIVE ANALYSIS OF METHODS FOR STUDYING THE ADHESION OF ANTIFRICTION COATINGS FOR FRICTION UNITS OF AUTOMOTIVE TECHNOLOGY AND TECHNOLOGICAL MACHINES

The article presents a study of the adhesive strength of adhesion of thin solid antifriction coatings. A brief analysis of existing methods for determining the adhesive strength of thin anti-friction coatings is performed. The method is described and experiments are carried out using a universal-purpose breaking machine with an electronic force meter IR5047-50 and a portable ad-hesive meter of the «Constant A» model. A number of quantitative estimates of the adhesion strength of the antifriction coating with the base are obtained. Conclusions are made about the adhesion strength of the coating and methods for determining its adhesion. Recommendations on the application of methods for determining the adhesive strength of thin solid antifriction coatings are given.

Improvement of the adhesive strength of adhesion bonds of textile products for the increasement of the efficiency of criminalistic support of law enforcement activities

Analysis of methods of chemical and physical modification and activation in the manufacture of garments made of polymeric materials is carried out. The analysis studied a wide range of possibilities for the use of nanotechnology in the garment industry and can serve as a theoretical basis for the manufacture of garments made of polymeric materials of various purposes, in particular for military and law enforcement agencies. The technology of rendering shape-resistant textiles, including clothing made of genuine leather, by use of the method of chemical modification and activation of its surface, which makes it possible to use more effectively various textile materials, in particular, leather at the cutting stage, is presented.

Study of the Adhesion Strength of the Coating with Different Coating Methods to the Surface of Parts of «Shaft» Type

The article deals with the strength of adhesion of coatings with the parts of type «shaft». In accordance with the above separation, gas-thermal methods of spraying and thermal power sintering have an adhesive interaction of particles and coatings. The use of thermomechanical treatment of preformed coatings (applied by thermal spraying) makes it possible to increase the adhesion strength of coatings with parts of «shaft» type. For a quantitative assessment of the adhesion strength of coatings with the base metal, a shear coating method was used. An experiment to determine the adhesion strength of samples of steel with various applied coatings is considered. It was concluded that the adhesion strength of the coatings obtained using the hydrogen-propane mixture was slightly superior.

The Influence of Temperature Impact on the Strength of Adhesion of Polyurethane Glue-foam with Masonry Products

The use of masonry on glued polyurethane foam joints can significantly increase labor productivity in the construction of stone buildings. One of the factors restraining the introduction of polyurethane foam adhesive into the practice of construction of stone buildings is insufficient knowledge of the influence of temperature effects on the adhesion of adhesive-foam to masonry products. In order to obtain data on the adhesion strength of polyurethane joints with masonry products under temperature influences, 28 prototypes of masonry were tested, aged in laboratory conditions and also subjected to heating to 100ºC and 200ºC. Tests of masonry samples were carried out in accordance with STB EN 1052-5. Based on the experimental studies carried out and new data on the influence of temperature effects on the adhesion strength of polyurethane joints with masonry products were obtained.

Controlling Binder Adhesion to Impact Electrode Mesostructure and Transport

The complex three-phase composition of lithium-ion battery electrodes - containing an ion-conducting pore phase, a nanoporous electron-conducting carbon binder domain (CBD) phase, and an active material (AM) phase - provides several avenues of mesostructural engineering to enhance battery performance. We demonstrate a promising strategy for engineering electrode mesostructures by controlling the strength of adhesion between the AM and CBD phases. Using high-fidelity, physics-based colloidal and granular dynamics simulations, we predict that this strategy can provide significant control over electrochemical transport-relevant properties such as ionic conductivity, electronic conductivity, and available AM surface area. Importantly, the proposed strategy could be experimentally realized through surface functionalization of the AM and CBD phases and would be compatible with traditional electrode manufacturing methods.

Modeling Arc Spraying Process for Eccentric Sleeve of Cone Crusher GP 500 Using Computer-Aided Design

This article deals with studying the technology of electric arc spraying of the eccentric body by selection of the copper-steel pseudo-alloy for spraying a covering. The part durability with the placed covering depends on the technology of spraying and the properties of the sprayed material. By increasing the strength of adhesion of the covering to the base it is possible to establish the optimal indicators of the coating mode. It became the main criterion of studying the arc spraying technology from the mathematical point of view.

Experimental studies of the strength of adhesion of fiberglass reinforcement with cement-sand concrete

The results of the study of the adhesion strength of fiberglass and metal fittings with concrete with different mechanical characteristics are presented. These characteristics were established after the normal curing of concrete B15-30; B25 concrete samples were subjected to alternating freeze-thawing. Testing of all samples was carried out on the digging of reinforcement at a special stand according to GOST 10060-2012. It is established that fiberglass reinforcement has a smaller amount of adhesion strength compared to steel; with increasing strength of concrete, the value of adhesion strength increases, after cycles of freezing and thawing, its fall slightly, but the amount of deformation increases.